JP2001090692A - Axial blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial blower capable of lowering blowing noises while reducing the peeling of the flow to be generated in a blade negative pressure surface and improved in molding property thereof at a low cost. SOLUTION: Plural blades 13 are arranged in the periphery of a boss part 12, to which a rotary shaft is fixed. Plural streamlined ribs 14 smoothly continued from a front edge thereof toward a blade rear edge part 13d are arranged in each blade 13 at a negative pressure surface 13a side front edge part 13c along the outline of the front edge with the predetermined space in the radial direction of a blower. These streamlined ribs 14 are arranged in plural lines 14a, 14b with the predetermined space in the circumferential direction of the blower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial blower suitable for, for example, an outdoor fan or a ventilator of an air conditioner.
In particular, the present invention relates to an axial blower that suppresses separation of a flow on a blade negative pressure surface to improve blowing performance and reduce blowing noise.

[0002]

2. Description of the Related Art FIG. 13 is a front view of a conventional axial flow blower 1 as viewed from the blade negative pressure side, and FIG.
FIG. 6 is a partially cutaway front view illustrating one wing and omitting other wings. The axial blower 1 is configured such that a plurality of blades 3, 3... Are integrally or integrally formed on a peripheral side surface of a cylindrical boss portion 2 having a rotating shaft (not shown) fixed to a central portion O at a predetermined pitch in a circumferential direction. Is formed. Each wing 3 has a concave arc-shaped leading edge 3a that forms an upstream end of the airflow with respect to the blower rotation direction (circumferential direction) indicated by an arrow in the drawing, and a rear edge that forms a downstream end of the airflow. 3b, a convex arc-shaped outer peripheral end 3c, a suction surface 3d on the fluid suction side also shown in FIG. 15, and a pressure surface 3e on the back surface thereof.
And

[0003] The leading edge 3 of each blade 3 on the suction side 3d side.
a is formed on the streamline thick portion 3f which is thicker than the trailing edge, and on the front edge 3a of the streamline thick portion 3f,
A plurality of streamline ribs 4 having a substantially rectangular front shape are connected to the front edge 3a.
Are arranged in a row at predetermined intervals in the radial direction of the blower along the contour line (outline).

FIG. 15 shows a circumferential cross section of a blade in a portion at an arbitrary distance r in the radial direction from an axis O of a rotating shaft (not shown) fixed to the center of the boss portion 2 as shown in FIG. I have.

[0005] As shown in FIG.
A streamline thick portion 3f is formed on the leading edge 3a on the d side,
Moreover, a plurality of streamline ribs 4 are provided on the streamline thick portion 3f.
Is disposed, the air flow U flowing from the blade-side negative pressure surface 3d side leading edge 3a passes through the streamlined rib 4 and becomes a vertical vortex street Uz. For this reason, it is possible to suppress the air flow from separating from the negative pressure surface 3d, so that the trailing edge portion 3b
The width of the wake vortex fu generated behind (downstream) the air can be reduced.

[0006]

However, in such a conventional axial-flow blower 1, there is a problem that the airflow noise reduction effect is not always sufficient because only one row of streamlined ribs 4 is arranged.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an inexpensive and compact mold that can further reduce the flow separation generated on the negative pressure surface of the blade and further reduce the blowing noise. And to provide a good axial flow blower.

[0008]

The invention according to claim 1 is
In the axial flow blower in which a plurality of blades are arranged on the outer periphery of the boss portion to which the rotation shaft is fixed, at the suction surface side front edge of each of the blades,
A plurality of streamlined ribs smoothly connected from the leading edge toward the blade trailing edge are arranged in a row along the contour of the leading edge at predetermined intervals in the radial direction of the blower. An axial blower characterized in that a plurality of rib rows are provided at predetermined intervals in a circumferential direction of the blower.

According to a second aspect of the present invention, each streamlined rib of the inner streamlined rib array provided on the inner side in the circumferential direction of the blower with respect to the outer streamlined rib array on the blade leading edge side guides the ventilation direction of the inflow air. 2. The axial blower according to claim 1, wherein the angle θa of the ventilation side surface is inclined in a range of 12 ° to 18 ° with respect to the angle θb of the ventilation side surface of the outer streamline rib row.

According to a third aspect of the present invention, each streamlined rib in the inner streamlined rib row is defined by a line segment OQ connecting the center of rotation axis O and an intersection Q between the blade outer periphery and the blade trailing edge. The axial flow blower according to claim 1 or 2, wherein each of the inclinations is increased at a predetermined angle from the outer periphery of the blade to the streamline rib on the boss side.

According to a fourth aspect of the present invention, in the inner streamlined rib array, the streamlined ribs are arranged at regular intervals in the radial direction of the blower, and the length L of each streamlined rib along the circumferential direction of the blower is set. _2, with respect to the length L ₁ along the fan circumferential direction of the aerodynamic ribs of the outer flow linear rib rows, according to claim 1, wherein the forming substantially the length of 0.8 L ₁ An axial flow blower according to any one of the preceding claims.

The invention according to claim 5 is characterized in that the inner streamline rib row is disposed at a position corresponding to the gap between the streamline ribs of the outer streamline rib row. The axial blower according to any one of claims 1 to 4.

According to a sixth aspect of the present invention, there is provided an inner streamlined rib array.
Each streamlined rib has its front edge in the circumferential direction
Connect each leading edge of each streamlined rib in the linear rib row in the circumferential direction of the blower
P is the center of the arc curve and r is its radius₁And when
Concentric with the center P and radius r ₁Radius r greater than₂of
3. The method according to claim 1, wherein the first and second radiators are positioned on an arc line.
Item 5. The axial blower according to any one of Items 5.

The invention according to claim 7 is characterized in that each streamline rib of the streamline rib rows on both the inner and outer sides is formed to have substantially the same width along the radial direction of the blower. Item 7. The axial flow blower according to any one of Items 1 to 6.

According to an eighth aspect of the present invention, in each streamline rib of the inner streamline rib row, an outer surface of a cross section along a circumferential direction of the blower forms an arc surface, and an arc curved surface of a part of the arc outer surface on the blade leading edge side. The axial flow according to any one of claims 1 to 7, wherein the radius Ra is integrally formed so as to be larger than the radius Rb of the arc-shaped curved surface at the other part on the opposite side. It is a blower.

According to a ninth aspect of the present invention, in each of the streamline ribs of the inner streamline rib array, the cross-sectional height along the blade thickness direction is gradually reduced from the boss toward the blade outer periphery. with removal strange is allowed to become gradually higher toward the blade outer peripheral side from the boss portion side opposite to the thickness of the part cross-section, the height of the nearest streamlined rib to the wing outer periphery and h _1, most to the boss aerodynamic rib height is taken as h ₂ close, h ₁
= It is an axial flow fan according to any one of claims 1 to 8, wherein it is set such that 2h _2.

According to each of these inventions, when each blade rotates around the axis of the boss by the rotation of the axial blower, the air flowing from the outside into the front edge on the negative pressure side of each blade. Passes through a plurality of rows of streamlined ribs to form a vertical vortex street, so that a transition is made from the laminar boundary layer to the turbulent boundary layer on the blade suction surface. In the turbulent boundary layer, separation of the airflow is less likely to occur than in the laminar boundary layer, and the width of the wake vortex that causes the blowing noise is narrowed, so that the blowing noise can be reduced. Moreover, since the streamlined ribs are arranged in a plurality of rows in the ventilation direction, the width of the wake vortex that causes the blowing noise is further reduced as compared with the conventional example in which the streamlined ribs shown in FIG. Can be. For this reason, the blowing noise can be further reduced. Furthermore, since each streamline rib can be easily formed integrally with each blade by, for example, resin molding, the moldability is good and the manufacturing cost can be reduced.

Further, of these inventions, claims 4 to 8
According to the invention, since the vertical vortex street can be stably generated on the blade negative pressure surface, the effect of reducing the blowing noise can be further increased.

According to the ninth aspect of the present invention, the height of each streamlined rib and the cross-sectional thickness of the leading edge including the thickness of the leading edge of the blade are substantially equal at any point in the radial direction of the blower. Therefore, when the axial blower is integrally molded by resin molding, the axial blower can be prevented from being thinned, and the cooling time can be shortened, so that the molding cost can be reduced.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG. In these figures, the same or corresponding parts are denoted by the same reference characters.

FIG. 1 is a front view showing the entire configuration of an axial blower 11 according to an embodiment of the present invention as viewed from the blade suction side, and FIG. 2 is a view showing one blade and other blades. FIG. 2 is a partially cutaway front view showing the illustration. As shown in these figures, the axial blower 11 has a plurality of blades 13, 13, 13 integrally or integrally attached to the outer peripheral side surface of a cylindrical boss portion 12 at, for example, circumferentially equal positions. It is integrally formed by resin molding or the like.

The boss portion 12 has a small cylindrical boss 12b for inserting and fixing a rotating shaft of a drive motor (not shown) in the center of the inside of the bottomed cylindrical main body 12a.
A substantially inverted Y-shaped connecting rib 12c extending radially from 2b and integrally connected to the inner peripheral surface of the boss main body 12a is integrally connected.

On the other hand, each blade 13 has a suction surface 1 on the air suction side.
3a, a positive pressure surface 13b, which is a blow side on the back surface, and each blade 13 with respect to a blower rotation direction indicated by an arrow in FIGS.
A concave front edge 13c forming an upstream end of the airflow of
A trailing edge portion 13d serving as a downstream end portion of the airflow and a convex arc-shaped outer peripheral end portion 13e formed by integrally connecting radially outer ends of the leading edge portion 13c and the trailing edge portion 13d are integrally formed. are doing.

Each wing 13 has a substantially rectangular front surface and a front edge 13c on the front edge 13c on the side of the suction surface 13a.
A plurality of streamlined ribs 14 smoothly connected from the front edge (front end) to the rear edge 13d in the blower radial direction at equal intervals along the contour (outline) of each front edge 13c. The outer streamlined rib row 14a is formed by arranging the outer streamlined rib rows 14a. Further, a plurality of streamlined ribs 14 are arranged at predetermined equal intervals in the radial direction of the blower at a predetermined distance from the outer streamline rib row 14a toward the trailing edge 13d in the circumferential direction of the fan (that is, the inner surface of the blade). The inner streamlined rib rows 14b are formed in a row, and the inner and outer streamlined rib rows 14b and 14a are provided in parallel.

[0025] Each aerodynamic ribs 14 of the inner flow linear ribs column 14b as shown in FIG. 2, the ventilation side 14b ₁ for guiding the airflow direction of the air flow, the outer flow linear ribs column 14a of the outer vicinity Ventilation side 14 of each streamline rib 14
and it is inclined at an angle θ with respect to a _1, as the the angle θ is set in a range of for example 12 ° ~ 18 °.

Further, the ventilation side 14b ₁ of each aerodynamic ribs 14 of the inner flow linear ribs column 14b as shown in FIG. 3, blower rotational center, i.e. the center O of the boss portion 12, after the trailing edge portion 13d The line OQ connecting the edge and the intersection point Q of the blade outer periphery 13e is also inclined at predetermined angles α ₁ , α ₂ , α ₃ ... Α _n . Moreover, these inclination angles α _{1 to} α _n are:
Vent side 14 of streamlined rib 14 closest to blade periphery 13e
b ₁ angle α closest streamlined ribs 1 from ₁ on the boss portion 12
Gradually inclined angle toward the angle αn of the ventilation side 14b ₁ of 4 increases, is set to α _n = 2α _1.

FIG. 4 shows an axial blower 1 constructed as described above.
The state of the air flow U on the side of the first blade negative pressure surface 13a is indicated by an arrow line. Figure 5 is a blade section when cut to the blower circumferential direction at any position of a predetermined distance r ₁ apart blades 13 in the radial direction from the center of the boss portion 2 as shown in Figure 4, the air flow U flowing through the airfoil section The state of is shown. In these figures, the arrow lines indicate the flow direction of the air, and the rotation of the arrow lines indicates the vertical vortex street Uz.

As shown in FIGS. 4 and 5, in the axial flow blower 11, the air flow U flowing from the leading edge fillet of the leading edge portion 13c onto the blade suction surface 13a is transmitted to the outer streamlined rib row 14a. It passes through the inner streamlined rib row 14b and becomes a longitudinal vortex row Uz, and transitions from the laminar boundary layer to the turbulent boundary layer on the blade suction surface 13a. Thereby, the width of the wake vortex fz which causes the blowing sound can be narrowed to reduce the blowing sound.

Moreover, according to the axial blower 11, since the streamlined ribs 14 have two inner and outer rows 14b and 14a, the air flow U passes through the inner and outer streamlined rib rows 14b and 14a. Thereby, the vertical vortex street Uz can be generated twice on the blade negative pressure surface 13a. For this reason, the generation amount of the vertical vortex row Uz can be increased as compared with, for example, the conventional axial flow fan 1 shown in FIG. The width of fz can be further reduced, and the amount of air blow can be further reduced. The streamline rib 14b is 3
More than one row may be provided.

[0030] Then, the inner flow linear ribs column 14b as shown in FIG. 6, the longitudinal length L ₂ along the fan circumferential direction of the aerodynamic ribs 14, the outer flow linear rib row 14a
It is formed shorter, formed for example in 0.8 L ₁ than the longitudinal length L ₁ along the fan circumferential direction of the aerodynamic ribs 14. In addition, the radial intervals W of the streamline ribs 14 in the inner streamline rib row 14b are set to be substantially equal.

Further, as shown in FIG. 7, each streamline rib 14 of the inner streamline rib row 14b is replaced with the outer streamline rib row 14b.
It is disposed at a position corresponding to the gap between the streamline ribs 14 adjacent to each other in the radial direction of the blower a.

Further, as shown in FIG. 8, the center of a virtual arc curve 15a connecting the leading edges (right ends in FIG. 8) of each streamline rib 14 of the outer streamline rib row 14a is P, and its radius is When ra is set, the front edge of each streamline rib 14 of the inner streamline rib row 14b is positioned on a virtual arc curve 15b concentric with the center P and having a radius rb larger than the radius ra. Has been placed.

Further, as shown in FIG. 9, the radial width Wa of each streamline rib 14 in the outer streamline rib row 14a and the radial width of each streamline rib 14 in the inner streamline rib row 14b. Wb is formed to have substantially the same width.

FIG. 10 shows an arc-shaped cross section 14c when each streamline rib 14 of the inner streamline rib row 14b is cut along the circumferential direction of the blower.
When the radius of curvature of the front half portion 14c1, which is a part of the wing front edge portion 13c side, is rc, and the radius of curvature of the rear half portion 14c2, which is the other portion, is rd, rc> rd is established.

By the way, as shown in FIG. 11, the thickness h _{0 of the} blade section of the leading edge 13c of each blade 13 along the radial direction of the blower.
Is gradually reduced from the boss 12 side Za to the blade outer periphery 13e side Zb.

On the other hand, as shown in FIG.
4 from the boss portion 12 side Ya to the blade outer periphery 13e side Yb
The height h ₁ of the streamline rib closest to the blade outer periphery 13 e and the height h ₂ of the streamline rib 14 closest to the boss portion 12 are h _1. =
It is formed so as to 2h _2. That is, the direction in which the height of each streamline rib 14 increases and the direction in which the thickness of the blade suction surface side front edge 13c increases are exactly opposite, so that the thickness h _{0 of the} front edge 13c. cross-sectional thickness h _t, including the
Becomes almost equal at any point. For this reason, it is possible to shorten the cooling time of the integral molding due to the resin molding of the axial blower 11 and to prevent or reduce the undercut or the like.

As described above, the axial blower 11 has the length L ₂ in the longitudinal direction of each streamline rib 14 of the inner streamline rib row 14b, the installation interval W, the installation position, the position of the front edge, the width Wb,
Since the curvature and the like of the outer surface of the circular arc are respectively set, the vertical vortex street can be stably generated on the blade negative pressure surface 13a, so that the blowing noise can be further reduced.

[0038]

As described above, according to the present invention, a plurality of rows of streamlined ribs that smoothly extend from the leading edge of the blade are arranged side by side on the suction surface side front edge of each blade. , A vertical vortex street of the air flow can be generated, and the separation of the flow can be suppressed. As a result, the wake vortex width formed behind the trailing edge of the blade can be reduced to reduce the blowing noise. In addition, since each streamline rib has a streamline shape, the axial blower can be easily and integrally molded by, for example, resin molding, thereby improving moldability and reducing manufacturing costs.

[Brief description of the drawings]

FIG. 1 is a front view of the overall configuration of an axial blower according to an embodiment of the present invention when viewed from a blade negative pressure surface side.

FIG. 2 is a partially cutaway front view for explaining an inclination angle of a ventilation side surface of each streamline rib in an inner streamline rib row of the axial flow fan shown in FIG.

FIG. 3 is a partially cutaway front view in the case of changing the inclination angle of each streamlined rib in the inside streamlined rib row of the axial blower shown in FIG. 1;

FIG. 4 is a partially cutaway front view showing a state of air flow on a blade negative pressure surface of the axial blower shown in FIG. 1 and the like.

[5] blade section view taken along the fan circumferential direction at a radius r ₁ wings axial blower shown in FIG.

FIG. 6 is a partially cutaway front view showing a longitudinal length of each streamlined rib and an arrangement interval between each rib in an inner streamlined rib row of the axial blower shown in FIG. 1 and the like.

FIG. 7 is a partial cutout in a case where each streamlined rib of the inner streamlined rib row in the axial flow fan shown in FIG. 1 and the like is arranged at a position corresponding to a gap between the streamlined ribs of the outer streamlined rib row; Front view.

FIG. 8 is a partial cutaway showing the positional relationship between the leading edge of each streamlined rib in the outer streamlined rib row and the leading edge of each streamlined rib in the inner streamlined rib row in the axial blower shown in FIG. Front view.

FIG. 9 is a partially cutaway front view for explaining the width of each streamline rib of the inner and outer streamline rib rows in the axial blower shown in FIG. 1 and the like.

FIG. 10 is a longitudinal sectional view of each streamline rib shown in FIG. 1 and the like.

11 is a cross-sectional view of a front edge portion of the axial blower shown in FIG. 1 and the like, taken along a radial direction of the blower.

FIG. 12 is a schematic diagram showing a cross section when the boss portion and the inner streamline rib row shown in FIG. 1 and the like are cut along the radial direction of the blower.

FIG. 13 is a front view of a conventional axial blower as viewed from a negative pressure side.

FIG. 14 is a partially cutaway front view showing one blade of the conventional axial flow fan shown in FIG.

FIG. 15 is a cross-sectional view of the blade when the blade is circumferentially cut at an arbitrary radius from the rotation center of the axial blower shown in FIG. 13;

[Explanation of symbols]

 Reference Signs List 11 axial flow blower 12 boss portion 13 blade 13a suction surface of blade 13c leading edge of blade 13d trailing edge of blade 13e outer peripheral end of blade 14 streamlined rib 14a outer streamlined rib row 14b inner streamlined rib row 15a, 15b Outer and inner arc curves

Claims (9)

[Claims] 1. An axial flow blower having a plurality of blades disposed on an outer periphery of a boss portion to which a rotating shaft is fixed, wherein: a front surface of each of the blades has a suction surface side; A plurality of streamlined ribs that are smoothly connected are arranged in a row along the contour of the front edge at predetermined intervals in the radial direction of the blower, and the streamlined rib rows are arranged in a predetermined manner in the circumferential direction of the blower. An axial blower characterized by having a plurality of rows provided at intervals. 2. Each streamlined rib of an inner streamlined rib array provided on the inner side in the blower circumferential direction with respect to the outer streamlined rib array on the blade leading edge side has an angle θa of a ventilation side surface for guiding the direction of airflow of the inflow air. 2. The axial flow blower according to claim 1, wherein said outer streamlined rib row is inclined at an angle of 12 [deg.] To 18 [deg.] With respect to the angle [theta] b of the ventilation side surface. 3. Each streamline rib of the inner streamline rib row is inclined at a predetermined angle with respect to a line segment OQ connecting the rotation axis center O and an intersection Q between the blade outer periphery and the blade trailing edge. 3. The axial flow blower according to claim 1, wherein each of the inclination angles increases from the blade outer periphery to the streamline rib on the boss portion side. Wherein the inner flow linear ribs column while arranged at equal intervals each of its streamlined ribs blower radially, the length L ₂ along the blower circumferential direction of each of these aerodynamic ribs, outer streamlined the length L ₁ along the fan circumferential direction of the aerodynamic ribs of the rib row
Relative, axial flow fan according to claim 1, characterized in that it is formed almost the length of 0.8 L _1. 5. The inner streamlined rib array, wherein the streamlined ribs are arranged at positions corresponding to the gaps between the streamlined ribs of the outer streamlined rib array. The axial flow blower according to any one of the above. 6. Each streamline rib of the inner streamline rib row has a center of an arc curve connecting each front edge of the streamer ribs of the outer streamline rib row in the fan circumferential direction. P,
The radius is taken as r _1, to any one of claims 1 to 5, characterized in that it is positioned on the center P and concentric with and arc lines of the large radius r ₂ than the radius r ₁ An axial blower as described. 7. The streamlined ribs of the inner and outer streamlined rib rows are formed to have substantially the same width along the radial direction of the blower. 2. The axial blower according to claim 1. 8. Each of the streamline ribs of the inner streamline rib row has an outer surface having a circular cross section along a circumferential direction of the blower, and a radius Ra of a circular arc surface of a part of the circular outer surface on the blade leading edge side is larger. ,
2. The structure as claimed in claim 1, wherein said second portion is integrally formed so as to be larger than a radius Rb of the arcuate curved surface at the other portion on the opposite side.
The axial blower according to any one of claims 1 to 7. 9. Each of the streamline ribs of the inner streamline rib row has a cross-sectional height along the blade thickness direction which is gradually reduced from the boss portion side toward the blade outer peripheral portion. with removal strange is allowed to become gradually higher toward the boss portion side blade outer peripheral side Conversely, the height of the nearest streamlined rib to the wing outer periphery and h _1, the closest streamlined ribs to the boss height of a is taken as h _2, axial flow fan according to any one of claims 1-8, characterized in that it is set such that h 1 ₌ 2h _2.